Patent Document No. 1 discloses a technique for measuring the distance to an object (or target) which is either standing still or moving based on a plurality of images that have been captured by a single image sensor by projecting light time-sequentially from multiple light sources onto the object.
Non-Patent Document No. 1 discloses a gesture interface system for detecting a human hand's motion with a near-infrared ray, and says that a human being's skin exhibits a higher reflectance to an infrared ray with a wavelength of 870 nm than to an infrared ray with a wavelength of 970 nm.